Offline Sync Queue Mobile App

My field crews often find themselves well beyond reliable reception, yet they still need to capture photos and short videos, tag them with a few details, and trust everything will reach our server once a signal returns. I need a true offline-first mobile app—built for both iOS and Android—that keeps every file and form safely on-device, adds it to a robust sync queue, and then reconciles everything automatically when connectivity is restored.

Here’s the workflow I have in mind:
• While offline, a user can shoot photos or video, enter a caption, select a job site, and hit “Save”.
• The app stores each item locally, shows a clear status badge (“Queued”, “Syncing”, “Synced”, or “Conflict”), and lets the user continue without worrying about coverage.
• Once any connection is detected—Wi-Fi or cellular—the queue syncs to our backend in order, retries intelligently, and resolves conflicts (e.g., two people editing the same record) with predictable logic we agree on up-front.
• If the signal drops mid-upload, progress is tracked and automatically resumes.

What I need from you:
1. An offline-first architecture using a local database (SQLite, Realm, or similar) and a background sync service.
2. Conflict-resolution rules implemented and surfaced in the UI so users always know the status of their data.
3. A straightforward, friendly interface that works the same on iOS and Android—React Native or Flutter are both fine by me if they speed things up and keep one codebase.
4. Source code, build instructions, and a concise technical document explaining how the queue, retry logic, and conflict handling work.
5. A short test plan showing how you’ll prove no data is lost through multiple offline/online cycles.

Acceptance criteria will be:
• Create 20+ media entries completely offline, toggle Airplane Mode on/off randomly, and confirm 100 % sync to the server.
• Visible, accurate status for every entry at all times.
• No duplication or overwriting of concurrent edits according to the agreed conflict rules.

If this sounds like your sweet spot, tell me how you’d tackle the local storage layer, the sync engine, and the cross-platform UI.